Testing circuit for telephone systems



June 29, 1937. e. c. BIERSTEDT TESTING CIRCUIT FOR TELEPHONE SYSTEMS Filed July 8, 1936 2 Sheets-Sheet l lNVENTOR G.C.B/ER$TEDT ATTORNEY Patented June .29, 1937 S'E'TES TESTING CIRCUIT FOR TELEPHONE SYSTEMS Gustav Carl Bierstedt Upper Montclair, N. J.,

Application July 8, 1936, Serial No. 89,646

7 Claims.

This invention relates to telephone systems and more particularly to test circuits for determining if the coin box apparatus of a telephone line functions properly.

In all telephone exchange areas there are always several lines equipped with coin boxes in which coins must be deposited in payment for calls made therefrom. In some exchange areas these coin boxes are used largely in public places 10 such as railroad stations, drug stores, etc. However, in other areas service to regular subscribers is furnished on thisbasis rather than on fiat rate or message register basis. Furthermore in large dial switching areas all local calls are charged for in accordance with the zone of the exchange area in which such calls are terminated and also in accordance with the duration of each call.

In all exchange areas, coins deposited in the coin box of a coin box line are collected on successful calls or refunded on uncompleted calls under the control of apparatus at the central office. In some instances complaints have been made or the operating company suspects that calls have been incorrectly charged or that on uncompleted calls deposited coins have not been refunded. It is therefore the object of the present invention to provide a testing equipment which may be applied to the coin box of a line to make a check or" the operation of such coin box.

In accordance with the present invention, a fixture is provided, which may be temporarily installed on the coin box magnet, having two sets of contacts closable respectively when the coin box magnet is operated to collect or refund deposited coins. This fixture is connected to a portable test box equipped with a pair of opposite ly polarized relays whose windings may be connested in series with the coin box magnet windings to indicate the polarity of the operating ourrent applied at any time to the coin box magnet, a group of relays whose circuits are controlled by the contacts of the fixture and by the polarized relays and a group of peg count meters or registers.

The circuits of the test box are so arranged that the total collect impulses received by the coin box magnet are registered on one register; the total refund impulses received by the coin box magnet are registered on a second register; the number of times the coin box magnet armature moves to the collecting position on collecting impulses is registered on a third register; the number of times the coin box magnet armature moves to the refunding position on collecting impulses is registered on a fourth register; the

number of times the coin box magnet armature moves to the refunding position on refunding impulses is registered on a fifth register; and the number of times the coin box magnet armature moves to the collecting position on refunding impulses is registered on a sixth register. From an observation of the registers over the period during which the test is conducted a determination of whether the complaint was justified or not may be made.

For a clearer understanding of the invention 10 reference may be had to the following detailed description taken in connection with the attached drawings of which:

Figure 1 shows a standard coin box magnet with the testing fixture attached thereto; 15

Fig. 2 is a perspective View of the fixture as seen from the underside showing two pair of contact springs operable respectively in the collecting and refunding positions of the coin box magnet armature; and

Fig. 3 shows the coin box circuit of a typical coin box line and the circuits of the test box.

The magnet structure of a coin box of the general type fully disclosed in Patent No. 1,117,485, granted November 17, 1914 to O. F. Forsberg, is shown in Fig. 1. This structure comprises two magnet coils l and 2 mounted on cores one of which is shown at 3, attached to the yoke 4. Near their pole faces the cores are united by a bridge 5 having an upturned extension on either edge thereof to which the armature structure is pivoted by two trunnion screws, one of which is shown at 6. The armature structure comprises an armature l, a plate 8 and two centering and restoring yokes one of which is shown at 9 all mounted on the trunnion screws. The plate 8 partakes of the movement of the armature and is provided on each end with a downwardly extending arm it adapted when the armature is rotated to engage the bridge 5 to 40 limit such rotary movement. The plate 8 is also provided with an extension H having an insulating roller l2 for operating the contact springs l3 and i4 and a further downwardly extending arm (not shown) for operating the coin distributing mechanism in the associated coin chute. Since the remaining structural details of the magnet structure are not directly concerned with the present invention, they will not be described in detail herein, but reference may be had to the 50 aforesaid Forsberg patent for such description.

The testing fixture for use in testing the operation of the coin box magnet comprises an L- shaped supporting plate having a top portion l5 and a side portion it. The side portion 56 is cut away at H to give clearance for the trunnion screw 5 and, to enable the plate to be positioned accurately with respect to the magnet structure when it is assembled thereon, the side portion i6 is provided with a notch I8 for engagement with the contact spring guard l9 formed integral with one of the upturned extensions of bridge 5 and with an inturned leg 20 which engages with the upper surface of bridge 5 immediately above the magnet coil I. For rigidly but detachably securing the supporting plate in the proper position with respect to the magnet structure, that is, with its top portion overlying the armature structure of the magnet and its side portion abutting the side extension of the bridge 5 with the leg 20 resting on the bridge 5 and the notch i8 engaging the guard l9, clamping strap 2! is provided which is secured to the side portion it of the plate by the knurl-headed screws 22 and 23. The strap 2| is adapted to engage back of the side extension of bridge 5 and, when the screws are tightened, clamps the side extension of bridge 5 securely between the strap 2| and the side portion it of the plate.

On the underside of its top portion 15 the supporting plate carries two contact spring pile-ups each comprising a pair of contact springs. One

spring pile-up comprises the contact springs 24 and 25, each having a connection terminal, the springs being suitably insulated from each other and from the plate and secured to the plate by screws 25 and 21. The spring 25 is provided with an insulating stud 28 which engages with the left end of the armature structure, whereby when the armature l is rotated in a direction to collect a deposited coin, the springs 24 and 25 are closed. The second spring pile-up comprises the contact springs 29 and 30 each having a connection terminal, the springs being suitably insulated from each other and from the plate and secured to the plate by screws 3! and 32. The spring 35 is provided with an insulating stud 33 which engages with the right-end of the armature structure whereby when the armature l is rotated in a direction to refund a deposited coin, the springs 29 and 35 are closed. The screws 54 are provided for adjusting the springs 29 and 36 and two similar screws one of which is shown at 35 are provided for adjusting springs 24 and 25. Having now described the testing fixture and the manner in which the pairs of contacts thereof are operated in response to the operation of the coin box magnet for collecting or refunding a deposited coin, the apparatus and circuits of the test box controlled thereby will be described.

Referring to Fig. 3, a subscribers substation is shown at 36 terminating at the central oifice in the bank of a line-finder 3i. The substation is also provided with a coin box, the magnet of which is schematically disclosed. The central office equipment for applying operating current to the coils l and 2 of the coin box magnet is schematically indicated byrelays 38, 39 and 40 and the sources of positive 110 volt collecting current 4! and negative 110 volt refunding current 42.

Preparatory to making a test, the testing fixture is installed on the coin box magnet structure as previously described and the contacts thereof connected to terminals on the terminal strip 43 of the test box. 'Also the normal ground connection from the coin box spring i3 is intercepted and spring i3 is connected to terminal 44 on the strip 43. Terminal 450m strip 43 is then connected to ground. With the coin box apparatus thus connected, spring 24 is connected through the winding of relay 48 to battery, spring 29 is connected through the winding of relay 45 to battery, springs 25 and 36 are both connected to ground and the windings of polarized relays 46 and 41 are interposed betweenv spring l3 and ground. The apparatus is now in condition for the running of a test.

It will be assumed that the subscriber to initiate a call deposits a coin in the coin box thereby causing the closure of contacts l5 and I4 and removes his receiver from the switchhook. In the well known manner the line-finder 3'! is now operated to extend the calling line to the central office equipment and the desired connection is then established in response to the operation of the substation dial in the usual manner. If the call is successfully established, relays 38 and 39 will be operated thereby applying coin collecting current from the source of collecting current 4! over the contact of relay 39, contacts of relay 38, tip and ring brushes of line-finder 31, thence in the usual manner through the windings l and 2 of the coin box magnet, springs l3 and i4 now closed by the deposited coin, over terminal 44, through the windings of polarized relays 46 and 4t and terminal 45 to ground. The armature of the coin box magnet should now operate to its collecting position thereby closing contacts 24 and 25 and polarized relay 45 should operate. Relay 45 is poled to respond only when collecting current is applied to the coin box magnet and relay 4'! is oppositely poled to respond only when refunding current is applied to the coin box magnet.

If the coin box magnet operates its armature to its collecting position as it should and thereby closes the contacts 24 and 25, the circuit of relay 48 will now be completed from battery through the winding of relay 48 and contacts 24 and 25 to ground and, with polarized relay 46 also operated, the operating circuit of relay 55 will becompleted from battery, winding of relay 55 to ground over the contacts of relay 45. Relay 48 upon operating locks over its inner upper front contact, the back contact of relay 53 to ground at the upper front contact of relay 50 and relay 5!) locks over its inner upper front contact to ground at the upper back contact of relay 52 and also to ground at the upper front contact of relay 48. With relays 48 and 54 both locked operated independent of the continued energization of the polarized relay 45 and the continued closure of contacts 24 and 25, the circuit of meter 54 is established from battery, winding of meter 54 and the inner lower front contact of relay 48 to ground at the lower contact of relay 5B. The

operating circuit of meter 58 is also established applied to the coin box magnet.

When meter 54 operated, it closed an obvious operating circuit for slow-to-operate relay 53 which at its back contact opens the locking circuit of relay 48 which thereupon releases opening the circuit of meter 54 and one looking circuit of relay 59. When meter 58 operated, it

'closed an obvious operating circuit for slow-tooperate relay 52 which at its back contact opens the other locking circuit of relay 5!] which now releases opening the operating circuit of meter that coin collecting current leases opening the upper 58. When the meters 54 and 58 release, they open t e circuits of relays 53 and 52 which now release. Relays 52 and 53 are made slow to operate to insure that the operating circuits of operated meters will not be opened until such meters have had sunicient time to become fully operated.

It will now be assumed that for some reason the coin box magnet operated its armature to the refunding position when coin collecting current was applied thereto from source 45' thereby closing contacts 29 and 39 and that polarized relay 45 operated indicating that collecting current was correctly applied. In. this case the closure of ccntacts29 and 39 will establish a circuit for relay -9 extending from battery through its winding and contacts 29 and 99 to ground and the operation of relay 45 will cause the operation of relay 59 in the manner described. Relay 49 upon operating looks over its inner upper front contact, the back contact of relay 53 to ground at upper front contact of relay 59 and relay 50 looks over its inner upper front contact to ground at the back contact of relay 52 and also to ground at the upper front contact of relay 419. With relays 15 and 59 now both operated, the circuit of meter 55 is established from battery through its winding and the inner lower front contact of relay 39 to ground at the lower contact of relay Relay 55 upon operating also establishes the circuit of meter 58. The operation of meter 55 registers the fact that the coin box magnet has operated erroneously to refund the deposited coin when it should have operated to collect the coin and the operation of meter 58 registers the fact was applied to the coin box magnet.

When meter 59 operated, it closed an obvious operating circuit for relay 53 which at its back contact opens the locking circuit of relay 59 which thereupon releases opening the circuit of meter 55 and one looking circuit of relay 59. When meter operated, it closed an obvious operating circuit relay 52 which at its back contact opens the other locking circuit of relay 59 which now rethe operating circuit of meter 53. When the meters 55 and 58 release, they open the circuits of relays 55 and 52 which also release.

It will now be assumed that the call made by the calling subscriber was unsuccessful and that relays 58 and 95 were operated to apply refunding current from the source 52 to the coin box magnet for causing the refunding of the deposited coin. In this case the coin box magnet armature should operate to its refunding position thus closing contacts 29 and 59 and the polarized relay ll should operate. Relay 4'! upon operating closes an obvious circuit for relay 5| and the closure of contacts 29 and 39 establishes the circuit of relay 5-5 previously traced. Relay 59 upon operating looks over its inner upper front contact,

the upper back contact of relay 53 to the upper front contact of relay 5| and relay 5| looks over its inner upper front contact to ground at the back contact of relay 52 and also to ground over front contact of relay 59. With relays 99 and 5| now both operated, the circuit of meter 5l| is established from battery through its winding and the lower front contact of relay 59 to ground at the lower contact of relay 5|. Relay 5! upon operating also establishes an obvious circuit for meter 59. The operation of meter 51 registers the fact that the coin box magnet has operated properly to cause the deposited coin to be refunded and the operation of meter 59 registers the fact that coin refunding current was applied to the coin box magnet.

When meter 57 operated it closed an obvious operating circuit for relay 53 which at its back contact opens the locking circuit of relay 49 which thereupon releases opening the circuit of meter 51 and one locking circuit of relay 5|. When meter 59 operated it closed an obvious operating circuit for relay 52 which at its back contact opens the other locking circuit of relay 5| which now releases opening the operating circuit of meter 59. When the meters 51 and 59 release, they open the circuits of relays 53 and 52 which also release.

It will now be assumed that for some reason the coin box magnet operated its armature to the collecting position when coin refunding cur rent was applied thereto from source 42, thereby closing contacts 24 and 25 and that polarized relay 4'! operated indicating that the refunding current was correctly applied. In this case the closure of contacts 24 and 25 will establish the operating circuit of relay 58 and the operation of relay 4'! will establish the operating circuit of relay 5|. Relay 58 upon operating looks over its inner upper front contact and the back contact of relay 53 to ground at the upper front con- 5! and relay 5| looks over its inner contact to ground at the back con- 52 and also to ground at the upper of relay 43. With relays 43 and 5| now both operated, the circuit of meter is established from battery through its winding and the lower front contact of relay 58 to ground at the lower contact of relay 5|. Relay 5| upon operating also establishes the circuit of meter 59. The operation of meter 55 registers the fact that the coin box magnet has operated erroneously to collect the deposited coin and the operation of meter 59 registers the fact that coin refunding current was applied to the coin box magnet.

When meter 55 operated, it closed the circuit for relay 53 which at its back contact opens the locking circuit of relay 48 which thereupon releases opening the circuit of meter 55 and one looking circuit of relay 5|. When meter 59 operated it closed an obvious operating circuit for relay 52 which at its back contact opens the other locking circuit of relay 5| which now releases opening the operating circuit of meter 59. When the meters 55 and 59 release, they open the circuits of relays 53 and 52 which in turn release.

It will be apparent from the foregoing description that so long as the test equipment is assoto the coin box magnet will be registered by the meter 58 and that each application of coin refunding current will be registered by the meter 59. Also each correct response of the coin box magnet when collecting current is applied thereto will be registered by meter 54 and each incorrect response will be registered by meter 55. Further that each correct response of the coin box magnet when refunding current is applied thereto will be registered by meter 51 and each incorrect respouse will be registered by meter 55. Thus by reading the meters prior to the starting of the test and by reading them again upon the termination of the test, the number of errors, if any, in the operation of the coin box magnet and their character may be ascertained and thereby the justification of the complaint made by the subscriber may be checked.

What is claimed is:

1. In a test device for testing the operation of a polarized relay which operates its armature in one direction in response to operating current of one polarity and in another direction in response to current of the opposite polarity, two pairs of contacts for said relay operable respectively by the movement of said armature in said two directions, relay means connectable into the operating circuit of said polarized relay for detecting the polarity of the operating current of said polarized relay and a plurality of registers operable under the joint control of said relay contacts and said relay means.

2. In a test device for testing the operation. of a coin box magnet which operates its'armature to a collecting position in response to operating current of one polarity and to a refunding position in response to current of the opposite polarity, a pair of contacts for said magnet closable when said armature moves to its collecting position, a second pair of contacts for said magnet closable when said armature moves to its refunding position, relay means connectable into the operating circuit of said magnet for detecting the polarity of the operating current of said coin box magnet, and a plurality of registers under the joint control of said magnet contacts and said relay means.

3. In a test device for testing the operation of a coin box magnet which operates its armature to a collecting position in response to operating current of one polarity and to a refunding position in response to current of the opposite polarity, a pair of contacts for said magnet closable when said armature moves to its collecting position, a second pair of contacts for said magnet closable when said armature moves to its refunding position, two oppositely polarized relays connectable into the operating circuit of said magnet for detecting the polarity of the operating current of said coin box magnet, and a plurality of registers operable under the joint control of said magnet contacts and said polarized relays.

4. In a test device for testing the operation of a coin box magnet which operates its armature to a collecting position in response to operating current of collecting polarity and to a refunding position in response to current of the opposite or refunding polarity, a first pair of contacts for said magnet closable when said armature moves to its collecting position, a second pair of contacts for said magnet closable when said armature moves to its refunding position, a first and a second polarized relay connectable into the operating circuit of said magnet and responsive respectively to current of collecting and refunding polarities, and a plurality of registers jointly controlled by said contacts and said polarized relays forregistering whether or not said coin box magnet correctly responds to current of collecting or refunding polarity.

5. In a test device for testing the operation of a coin box magnet which operates its armature to a collecting position in response to operating current or" collecting polarity and to a refunding position in response to current of the opposite or refunding polarity, a first pair of contacts for said magnet closable when said armature moves to its collecting position, a second pair of contacts for said magnet closable when said armature moves toits refunding position, a first and a second polarized relay connectable into the operating circuit of said magnet and responsive respectively to current of collecting and refunding polarities, a plurality of registers jointly controlled by said contacts and said polarized relays for registering whether or not said coin box magnet correctly responds to current of collecting or refunding polarity, and registers for registering respectively the number of times current of collecting or refunding polarity is applied to said coin box magnet.

6. In a test device for testing the operation of a coin box magnet, which operates its armature to a collecting position in response to operating current of collecting polarity and to a refunding position in response to current of the opposite or refunding polarity, a first pair of contacts for said magnet closable when said armature moves to its collecting position, a second pair of contacts for said magnet closable when'said armature moves to its refunding position, a first and a second polarized relay connectable into the operating circuit of said magnet and responsive respectively to current of collecting and refunding polarities, a first register operable upon the closure of said first contacts and the operation of said first polarized relay, a second register operable upon the closure of said first contacts and the operation of said second polarized relay, a third register operable upon the closure of said second contacts and the operation of said second polarized relay and a third register operable upon the closure of said second contacts and the operation of said first polarized relay.

7. In a test device for testing the operation of a coin box magnet which operates its armature to a collecting position in response to operating current of collecting polarity and to a refunding position in response to current of the opposite or refunding polarity, a first pair of contacts for said magnet closable when said armature moves to its collecting position, a second pair of contactsfor said magnet closable when said armature moves to its refunding position, a first and a second polarized relay connectable into the operating circuit of said magnet and responsive respectively to current of collecting and refunding polarity, a first register operable upon the closure of-said first contacts and the operation of said first polarized relay, a second register operable upon the closure of said first contacts and the operation of said second polarized relay, a third register operable upon the closure of said second contacts and the operation of said second polarized relay, a fourth register operable upon the closure of said second contacts and the operation of said first polarized relay, a fifth register operable upon each operation of said first polarized relay,

and a sixth register operable upon each operation of said second polarized relay.

GUSTAV C. BIERSTEDT. 

